A device is proposed which can continuously monitor an object ahead of a vehicle by selecting a detection result based on any of a wide-angle image captured by a wide-angle camera having a wide angle of view and a narrow-angle image captured by a narrow-angle camera having a narrow angle of view (see Japanese Patent Laid-Open Publication No. 2011-121398). Such a device selects a narrow-angle image when a distance to the object exceeds a distance in which an object can be detected with a desired accuracy by a wide-angle image, and a wide-angle image when an object is out of the field of view of the narrow-angle camera.
However, for the technology described in Japanese Patent Laid-Open Publication No. 2011-121398, there is no mention of a possibility of delay of determination of vehicle control due to recognition delay time or non-recognition, etc., occurred in switching detection results. The delay of determination to stop a vehicle may require a larger deceleration.